Earlier this week WhatsApp turned seven years old. It has been an amazing journey and in the coming months we're putting an even greater emphasis on security features and more ways to stay in touch with the people that you care about.

But anniversary dates are also an opportunity to look back. When we started WhatsApp in 2009, people's use of mobile devices looked very different from today. The Apple App Store was only a few months old. About 70 percent of smartphones sold at the time had operating systems offered by BlackBerry and Nokia. Mobile operating systems offered by Google, Apple and Microsoft – which account for 99.5 percent of sales today – were on less than 25 percent of mobile devices sold at the time.

As we look ahead to our next seven years, we want to focus our efforts on the mobile platforms the vast majority of people use. So, by the end of 2016, we will be ending support for WhatsApp Messenger on the following mobile platforms:

BlackBerry OS and BlackBerry 10

Nokia S40

Nokia Symbian S60

Android 2.1 and Android 2.2

Windows Phone 7

iPhone 3GS/iOS 6

While these mobile devices have been an important part of our story, they don't offer the kind of capabilities we need to expand our app's features in the future.

This was a tough decision for us to make, but the right one in order to give people better ways to keep in touch with friends, family, and loved ones using WhatsApp. If you use one of these affected mobile devices, we recommend upgrading to a newer Android, iPhone, or Windows Phone before the end of 2016 to continue using WhatsApp.

UPDATE: You won't be able to use WhatsApp on the following platforms for:

Nokia Symbian S60 after June 30, 2017

BlackBerry OS and BlackBerry 10 after December 31, 2017

Windows Phone 8.0 and older after December 31, 2017

Nokia S40 after December 31, 2018

Android versions 2.3.7 and older after February 1, 2020

Note: Because we will no longer actively develop for these platforms, some features may stop functioning at any time.